Gas control apparatus with a pressure regulator

ABSTRACT

A gas control apparatus with a pressure regulator selectively controls the setpoint of the regulator by an electrical current between a minimum and a maximum value of the gas outlet pressure. A diaphragm of the regulator is exposed to the pressure to be controlled and carries a closure member of a bleed valve. A control spring for determining the setpoint of the gas pressure acts between the diaphragm and an adjustable abutment. A solenoid actuator acts between a valve rod of a switch-on valve located between an inlet of the apparatus and the regulator and the abutment. A reset spring for the armature of the actuator acts between a stationary abutment and the armature to engage the armature after the armature has opened the switch-on valve. Thus, the solenoid actuator responds to an electrical current to control the operation of the switch-on valve to provide an inlet pressure for the regulator. The minimum and maximum setpoint levels can be separately adjusted by adjusting stops for the armature while the slope of the pressure/current characteristic is adjusted by adjusting a tension of the reset spring of the armature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to gas pressure control apparatus. Morespecifically, the present invention is directed to a gas controlapparatus having an adjustable outlet gas pressure.

2. Description of the Prior Art

Gas control apparatus for controlling a gas pressure is well-known inthe art for providing an outlet gas pressure regulated with respect toan adjustable setpoint. European Pat. No. 00 62 856 shows a gas controlapparatus with a gas pressure regulator where the setpoint of theregulator can be adjusted by means of a solenoid operator, which ismounted on the pressure regulator. This pressure regulator is suppliedvia a throttle and an actuator solenoid valve with the gas supplypressure as available at the inlet of the gas control apparatus, andthis pressure is used as auxiliary energy for the servo-pressureregulator. The regulator controls the pressure at the outlet of the gascontrol apparatus and for this purpose acts upon a diaphragm which withits opposite side engages a control spring. The stationary abutment ofthis control spring is adjusted by means of said solenoid operatortherewith adjusting the setpoint of the pressure regulator. It is alsoknown in the art to provide an electromagnetic actuator having avariable spring rate for an armature bias spring as shown in U.S. Pat.No. 4,290,040. This bias spring has a spring constant which depends onthe actual position of the armature of the solenoid and which increaseswhen the air gap between the armature and the magnetic core decreases.In order to achieve this the blade spring forming the control springabuts against a support which changes the effective length of the springdependent on the position of said armature. The present inventionprovides a gas control apparatus which works without such a specialcontrol spring with non-linear characteristic and furthermore is easierand less expensive to manufacture and to adjust.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved gas controlapparatus.

In accomplishing this and other objects, there has been provided, inaccordance with the present invention, a gas control apparatus with apressure regulator selectively controls the setpoint of the regulator byan electrical current between a minimum and a maximum value of the gasoutlet pressure. A diaphragm of the regulator is exposed to the pressureto be controlled and carries a closure member of a bleed valve. Acontrol spring for determining the setpoint of the gas pressure actsbetween the diaphragm and an adjustable abutment. A solenoid actuatoracts between a valve rod of a switch-on valve located between an inletof the apparatus and the regulator and the abutment. A reset spring forthe armature of the actuator acts between a stationary abutment and thearmature to engage the armature after the armature has opened theswitch-on valve. Thus, the solenoid actuator responds to an electricalcurrent to control the operation of the switch-on valve to provide aninlet pressure for the regulator. The minimum and maximum setpointlevels can be separately adjusted by adjusting stops for the armaturewhile the slope of the pressure/current characteristic is adjusted byadjusting a tension of the reset spring of the armature.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention may be had when thefollowing description is read in connection with the accompanyingdrawings, in which:

FIGS. 1a, 1b and 1c are a top view of a first cross-sectionalillustration and a second cross-sectional illustration, respectively, ofa gas control apparatus embodying an example of the present invention,

FIGS. 2a, 2b and 2c are schematic illustrations of the operatingconnection between the armature of the solenoid and the valve rod of theswitch-on valve and the operating pin of the pressure in differentoperating conditions; and

FIG. 3 is an illustration of a curve showing the relationship of theoutput pressure P of the pressure regulator versus the current I flowingthrough the coil of the solenoid.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1a, 1b and 1c, an upper part 1 of a housing supports asolenoid 2, a pressure regulator 3 and a switch-on valve 4. In FIG. 1cthe actual position of the pressure regulator 3 and the switch-on valve4 is shown whereas in FIG. 1b the switch-on valve 4 is offset withrespect to the servopressure regulator by an amount "A" to the left sidein order to avoid obscuring internal parts. The solenoid 2 consists of ayoke 5, an armature 7 connected to the yoke by means of a spring blade6, a magnetic core 8, and a coil 9 surrounding the core 8. The pressureregulator 3 carried by the upper portion 1 of the housing consists of adiaphragm 11, a control spring 12, a closure member 13 carried by thediaphragm 11, and a valve seat 14 working together with the closuremember 13. The closure member 13 and the valve seat 14 together form aservo valve. The control spring 12 has its end which is located oppositeto the diaphragm 11 held by a supporting piece 15 provided at the freeend of operating pin 16. A diaphragm chamber 17 located between thediaphragm 11 and the valve seat 14 is connected to an outlet side 19 ofthe gas control valve by means of a fluid channel 18. A chamber 20 belowthe valve seat 14 has one side connected via switch-on valve 4 and athrottle 21 to an inlet 22 of the gas control apparatus and on the otherside forms the operating chamber of a diaphragm operated gas controlvalve. This valve consists of a valve seat 23 provided between an inlet22 and a gas outlet 19 and an associated closure member 25 spring biasedin a closing direction by means of a spring 24. The pressure in theactuator chamber 20 acts in an opening direction via diaphragm 26 on theclosure member 25. The gas control valve 23, 24, 25, 26 is located in alower portion 27 of the housing which is attached to the upper portion 1with a sealing plate 28 provided between these two portions of thehousing.

If a high control pressure exists in the chamber 20, it opens, viadiaphragm 26, the control valve 23 to 25 further than in the case of lowcontrol pressure. To reduce the control pressure in chamber 20, theclosure member 13 can lift off from the valve seat 14 in order to bleedoff the control pressure within the chamber 20 to the outlet 19 of thegas control apparatus via the diaphragm chamber 17 and channel 18. Thedesign and operation of such kind of servopressure regulators iswell-known, e.g., from European Pat. Nos. 00 62 856 and 00 39 000.

The upper portion 1 of the housing further supports the switch-on valve4 as shown in FIGS. 1b and 1c and consisting of a valve seat 31 and aclosure member 33 carried by a valve rod 32 and further comprising asecond valve seat 34 located opposite the seat 31 and including apassage 35 to the outlet 19 of the gas control apparatus. A sealingdiaphragm 36 seals the chamber 37 on the upper side of the valve seat 33against the valve rod 32 extending through diaphragm 36. The chamber 37is connected to the inlet 22 of the gas control apparatus via thethrottle 21. The space between the two valve seats 31 and 34 of theswitch-on valve 4 is connected via a passage 38 to the actuator chamber(see FIG. 1b). A closure spring 34 abuts its one end against the upperportion of the housing and with its opposite end engages a collar 40 ofthe valve rod 32. This spring 34 biases the closure member 33 of theswitch-on valve 4 in a closing direction to valve seat 31.

When the switch-on valve 31, 33 is opened, an inlet pressure entersoperator chamber 20 via the throttle 21. In this manner, the operatorchamber 20 of the control valve 23 to 26 is provided with the requiredauxiliary energy, i.e., the inlet gas pressure. If the gas pressure atthe outlet 19 exceeds a setpoint as provided by the operating pin 16 viaa control spring 12, this pressure acts upon the lower side of thecontrol diaphragm 11 and moves this diaphragm 11 such that the closuremember 13 is lifted from the valve seat 14. The control pressure in theoperating chamber 20 is partially vented to the outlet 19 via the valve13, 14. Because of this reduction of the control pressure in the chamber20, the closure spring 24 of the control valve 23 to 25 can move itsclosure member 25 in the direction of a closing position. Therewith theclosure member 25 reduces the gas flow between the inlet 22 and theoutlet 19 and therewith also reduces the outlet pressure of the gascontrol apparatus. If on the other hand, the gas pressure at the outlet19 decreases and therewith also the force acting from below on thecontrol diaphragm 11 is reduced, then a higher control pressure buildsup in the operating chamber 20 because the bleed-off valve 13, 14 ismaintained closed by the force of the control spring 12. This increasedcontrol pressure in the chamber 20 moves the diaphragm 26 and with itthe closure member 25 of control valve 23 to 25 downwards whereby thecontrol valve 23 to 25 is opened further, and the outlet pressureincreases again.

By means of two rivets 41, a blade spring 42 is fixed to armature 7 ofthe solenoid with a free end 43 of said blade spring 42 acting upon thevalve rod 32 of the switch-on valve 4. For this purpose, valve rod 32 isprovided with a collar 44 where the free end 43 of blade spring 42engages with the end 43 having a bore through which the end 33 projects.An end portion 45 of the valve rod 32 has a reduced diameter and carriesa ring 46 in a surface groove. The valve rod 32 is biased by the resetspring 39 which with its one side abuts stationarily against anintermediate wall 47 and with its other side against collar 40 of valverod 32. A spring 39 acts in the closing direction of switch-on valve 31to 33.

Furthermore, by means of two rivets 51 relatively stiff cantilever 52 isfixed to armature 7. This cantilever is a flat blade with a bore 53being provided in its free end 53. An end portion 55 of the operatingpin 16 has a reduced diameter and projects through the bore 53. The pin16 has a collar 56 against which the free end 53 of the cantilever 52abuts during an operation for moving pin 16. The movement of pin 16 inan axial direction is limited by two abutments provided by rings 57 and58. The ring 57 cooperates with a threaded sleeve 59 which can beadjusted within a threaded busing 60. The bushing 60 can be adjusted ona thread 61 of stationary tube 62.

The cantilever 52 as shown in 1b is bent with its free end away from theplane of the armature 7 and is under the tension of a screw 63 having ahead which urges cantilever 52 in the direction toward armature 7. Thescrew 63 is screwed into a threaded bore of the armature 7. The armature7, as shown in FIG. 1c, is pushed away from a pole piece 65 of themagnetic core 8 by means of a reset spring 64. For this purpose, thespring 64 has one end abuting against the upper portion 1 of the housingand its other end engaging the free end of a transmission member 66 intowhich an adjustable adjustment screw 67 projects with a pin-likeprojection 68. The screw 67 can be adjusted with respect to the armature7. As soon as the pin projection 68 engages the bottom of thecylindrical bore of transmission member 66, the reset spring 64 pushesthe armature 7 away from the pole piece 65 by means of adjusting screw67. The armature 7 is further subject to the force of the valve rod 32which is spring biased by the closure spring 39. The valve rod 32 urgesthe armature 7 away from the pole piece 65 via the collar 44 and theblade spring 42.

In describing the operation of the gas control apparatus, reference ismade to FIGS. 2a, 2b and 2c, in which:

FIG. 2a shows the position of armature 7, valve rod 32 and operating pin16 in the position when the gas control apparatus is switched-off andthe switch-on valve 4 is closed,

FIG. 2b shows the position of the above-mentioned parts when theswitch-on valve 4 is opened but the pressure regulator is not yetacting, which means that a minimum outlet pressure is present at theoutlet of the gas control apparatus,

FIG. 2c shows the position of these parts when the pressure regulator isadjusted to an outlet pressure which lies between the minimum and themaximum outlet pressure, i.e., the pressure regulator is operatingwithin its modulating range.

If no current flows through the coil 9 the closure spring 39 keeps theswitch-on valve 31 to 33 closed via the collar 40 and the valve rod 32.The closure spring 24 keeps the closure member 25 of the gas controlvalve closed as well. Therewith, the outlet pressure P at the outlet 19of the gas control apparatus is zero (see FIG. 3). Under the influenceof the control spring 12, the operating pin 16 engages bushing 60 withits ring 58. Control spring 12 at this time has the least possiblespring bias.

As soon as the current through coil 9 is switched-on and reaches apredetermined minimum amount, the armature 7 tilts around the springjoint 6 and, by means of spring blade 42, presses the valve rod 32downwards against the force of the reset spring 39. Therewith theclosure member 33 is lifted from the valve seat 31, and gas can flowfrom the inlet 22 of the gas control apparatus via the throttle 21through the switch-on valve 31 to 33 into the operator chamber 20 of thediaphragm operator for the gas control valve 23 to 26. Simultaneously,the closure member 33 closes the opposite valve seat 33 and therewithcloses the connection between the operator chamber 20 and the passage 35to the outlet 19. As soon as a sufficient pressure has built up in thechamber 20, the diaphragm 26 moves the pin 29 of the closure member 25downwards and thereby moves the closure member 25 away from the valveseat 23 whereby gas from the inlet 22 can flow to the outlet 19. Thepressure at the outlet 19 simultaneously is supplied via the passage 18to the chamber 17 below the control diaphragm 11 of the pressureregulator.

If the outlet pressure exceeds above a value at which the force of thecontrol spring 12 acting upon the upper side of the diaphragm 11 exceedsthe force which by the gas pressure within the chamber 17 acts on thelower side onto the diaphragm 11, the closure member 13 is lifted fromthe valve seat 14, and the pressure within the operator chamber 20 isvented to the outlet 19 via the control valve 13, 14 at the passage 18.This reduction of the pressure results in a reduction of the forceacting upon the diaphragm 26 such that the closure spring 24 of thecontrol valve 23 to 26 moves its closure member 25 into a position ofreduced gas flow whereby the pressure at the outlet 19 is reduced again.A force balance is generated which determines the minimum gas pressure Pat the outlet 19. FIG. 3 shows in the range between I=0 to I=i₁ therange in which the armature 7 is moved but the switch-on valve 4 is notyet opened. At a current i₁, the switch-on valve 4 starts to open and,in the manner as described above, generates the minimum outlet pressureP_(min). The amount of this pressure can be adjusted by means of sleeve59 which as mentioned above cooperates with the ring 58 on the operatingpin 16. During the actuation of the switch-on valve 4, i.e., during thetransition from the position of the parts according to FIG. 2a to theposition of FIG. 2b, the adjusting screw 67 does not yet engage thetransmission member 66 of the reset spring 64, and cantilever 52 doesnot yet act upon the operating pin 16 via the collar 56.

When the current I is increased further and reaches a value i₂, theposition of the parts as shown in FIG. 2b is reached. Now the adjustingscrew 67 with its cylindrical projection 68 engages the bottom 69 of thetransmission member 66. Furthermore, the cantilever 52 has moved througha dead zone "Z" to collar 56 of operating pin 16, and when the currentincreases further it will move operating pin 16 by means of said collar56. Before this happens, the blade spring 42 has moved the valve rod 32so far that the reset spring 39 is heavily biased, and the closuremember 33 rests on the opposite seat 34. Therewith the closure member 33closes the passage 35 to the outlet 19 of the gas control apparatus. Ifthe current I increases above the value i₂, changes through themodulating range to value i₃, the cantilever 52 moves the operating pin16, as shown in FIG. 2c, downwards and compresses control spring 12.Therewith the force acting upon the upper side of diaphragm 11 isincreased. This force determines the outlet pressure of the gas controlapparatus. The further that the operating pin 16 is moved downwards, thehigher this force will become, and the higher will become the outletpressure fed into the chamber 17 via the passage 18 before this outletpressure via the diaphragm 11 is able to move the closure member 13 ofbleed valve 13, 14 away from its seat 14. This outlet pressure increasesthe force of the control spring 12 and opens valve 13, 14 whereby thecontrol pressure in the operating chamber 2 is vented to the outlet 19via the valve 13, 14 and the passage 18. Therewith the closure spring 24of the control valve moves its closure member 25 upwards and therewithreduces the gas flow through the valve and therewith also reduces theoutlet pressure P. With increasing current through the coil 9, theoutlet pressure P increases within the modulating range between currentvalues i₂ and i₃ as shown in FIG. 2c.

Finally when a current value i₃ is reached, the operating pin 16 ismoved so far downwards that the ring 57 engages threaded sleeve 59.Therewith the maximum outlet pressure Pmax is reached. This maximumpressure can be adjusted by means of turning sleeve 59 within bushing60. On the other hand, the minimum outlet pressure Pmin can be adjustedby screwing bushing 60 within thread 61 of the stationary tube piece 62.

As shown in FIG. 2b, as soon as the adjusting screw 67 engagestransmission member 66 by a further movement of the armature 7, thereset spring 64 is brought under tension as well. It therewith supportscontrol spring 12. By adjusting the screw 67 the amount or the influenceof the reset force generated by the spring 64 on the armature 7 can beadjusted. In this manner the steepness, i.e., slope, of thepressure/current characteristic within the modulating range may bechanged. The length of dead zone "Z" is adjusted by means of the screw63 which with its head engaging the cantilever 52 determines how muchthe centilever 52 is positioned away from the plane of armature 7. Anon-magnetic distance piece 70 on the armature 7 insures that thearmature 7 under no circumstances can engage the pole piece 65 and canstick to the pole piece 65.

For switching off the gas control apparatus the current I is interruptedso that the armature 7 under the influence of the reset spring 64 andthe control spring 12 moves back into the resting position as shown inFIG. 2a. The armature 7 with its blade spring 42 releases the valve rod32 so that the reset spring 39 can move the closure member 33 into theclosed position as shown in FIG. 2a. Therewith the pressure regulator isseparated from the inlet pressure by means of the closure member 33, andthe control pressure within the chamber 20 is vented via the passage 35to the outlet. As a result of this reduction of the control pressure theclosure spring 34 of the gas control apparatus moves closure member 35into the closed position.

An essential advantage of the present invention is seen in the fact theby means of a single solenoid operator and by using normal springs andother components the operation of the switch-on solenoid valve 4 as wellas the control of the setpoint of the pressure regulator can be achievedby an electrical current. Therewith the setpoint can be continuouslychanged between a minimum value and a maximum value of the outletpressure. Further, the minimum pressure as well as the maximum pressurecan be adjusted separately, and the steepness of the controlcharacteristic within the modulating range is also selectivelychangeable.

Accordingly, it may be seen that there has been provided, in accordancewith the present invention, an improved gas pressure regulator.

The embodiments of the present invention in which an exclusive propertyor privilege is claimed are defined as follows:
 1. A gas controlapparatus having a main valve which can be controlled by means of apressure regulator with a closure member of the main valve being biasedin closing direction by means of a spring comprisinga diaphragm of thepressure regulator which is exposed to the pressure to be controlledcarries a closure member of a bleed valve which connects a controlpressure chamber of the main valve to an outlet of the controlapparatus, a control spring determining the setpoint of the gas pressurebiasing said diaphragm, an adjustable abutment for an end of saidcontrol spring opposite said diaphragm, a switch-on valve biased by aclosure spring and located in the gas path between the inlet of the gascontrol apparatus and the pressure regulator, a solenoid consisting of acoil, a magnetic core and a tiltable armature has its armature on theone side contacting a valve rod of said switch-on valve and on the otherside contacting a pin carrying said abutment of said control springwhich is opposite said diaphragm and an armature reset spring has astationary abutment for one of its ends and engages said armature withits other end after said armature has moved through a dead zone strokewhich is sufficient for opening said switch-on valve.
 2. An apparatusaccording to claim 1, wherein a blade spring is fixed to said armature,said blade spring acting with its free end upon said valve rod, and acantilever extending essentially in parallel to said blade spring hasits fixed end also attached to said armature and a free end engagingsaid pin.
 3. An apparatus according to claim 2, wherein the relativeposition of said cantilever and said armature can be adjusted in theoperating direction of said pin.
 4. An apparatus according to claim 3,wherein said cantilever is a relatively stiff metal plate which isspaced from said armature between its free end and its fixed end, andthat an adjusting screw screwed into said armature projects through abore of said cantilever and said cantilever is spring biased in thedirection of said armature by means of a head of said adjusting screw.5. An apparatus according to claim 4, wherein the dead stroke zone isprovided between said cantilever and said operating pin of said pressureregulator with the dead stroke being adjustable by means of saidadjusting screw having such a length that the movement of said pin bymeans of said cantilever and the action of said armature reset springupon said armature start simultaneously.
 6. An apparatus according toclaim 1, wherein said armature reset spring carries at its free end asleeve-like transmission member and an adjusting screw adjustable withinsaid armature projects a projection pin into said transmission member toengage the bottom of said transmission member when said switch-on valveis opened, and subsequently said adjusting screw acts upon said armaturereset spring.
 7. An apparatus according to claim 1, wherein twoabutments are provided on said pin with both of said abutmentscooperating with adjustable counter abutments provided in said housingfor adjusting the minimum and the maximum outlet pressure of theapparatus.
 8. An apparatus according to claim 7, wherein both of saidcounterabutments are formed by threaded sleeves movable within a tubemember.
 9. An apparatus according to claim 1, wherein said armaturereset spring and said control spring are helical springs.